Missouri Republicans are growing increasingly despondent about their chances of reclaiming the governor’s mansion in 2012. Peter Kinder, the front-runner for the GOP nod, hasn’t even officially launched a campaign yet — but he’s already being privately written off by members of his own party.

What’s worse: They believe the lieutenant governor’s bizarre antics and undisciplined behavior have turned him into a punchline who could become a heavy drag at the top of the ticket.

It’s not that first-term Gov. Jay Nixon is invincible. While popular and mostly noncontroversial, he’s still a Democrat in a reddening battleground state that President Obama failed to carry in 2008.

The overwhelming concern — expressed in interviews by multiple GOP lawmakers and several party insiders — is that Kinder lacks the political acumen and personal likeability necessary to upend an incumbent.

“I don’t think he has a chance to beat Gov. Nixon. Every single person that I’ve talked to feels the same way,” said one GOP state senator, speaking on the condition of anonymity. “Everybody loves Jay Nixon and I have to say he’s done a pretty good job. The people I’ve talked to are just resigned to the fact that [Kinder’s] going to run and lose.”

Said another state representative: “I think the majority of legislators are concerned about where the Kinder campaign is going and how effective they are.”

Republicans refused to speak on the record about Kinder. He’s still the president of the state Senate, and took the reins of the party apparatus after agreeing to drop his brief 2008 gubernatorial bid to clear the way for Rep. Kenny Hulshof.

While he’s made no official announcement about the governor’s race, Kinder’s aspirations are hardly a secret. He’s told supporters and fundraisers privately for more than a year he plans on running, and a top adviser confirms Kinder is doing “everything to prepare for that.”

Kinder, who declined to comment, was always going to be an underdog to Nixon, a moderate former four-term attorney general. But it’s the self-inflicted wounds that have Republicans pulling their hair out.

After the St. Louis Post-Dispatch revealed in April that Kinder had billed the state for numerous stays at St. Louis-area hotels — more than two months’ worth per year, on average — he initially was defiant and blamed the media. But days later, the candidate who ran on the slogan “Every Dollar Counts” reimbursed the state more than $50,000 to cover any “questionable reimbursements.”

Not only had Kinder’s credibility been dented, but his recalcitrance allowed the incident to dominate the news cycle and provided a partisan counterweight to Democratic Sen. Claire McCaskill’s own problem involving back taxes owed on a personal plane.

“We thought we had a good hit on Claire with the whole travel thing and the next thing you know Peter Kinder’s on the front of the newspapers for the same thing. Between Claire and Jay on travel, we could’ve kept pounding them on it and then one of our members has the same faults. What do they say about rocks in glass houses?” said the GOP state representative.

A more enduring worry about Kinder, who is single, is his ubiquitous use of Twitter. At times, his tweets appear to be ill-timed or even tone-deaf.

He once retweeted a message referring to “tramp stamps,” and forwarded a message to his 3,000 followers, urging them to “go vote for [a] hot wife in the Top 25 Political Mom blogs” just a day after his home state was ravaged by the worst tornado in 50 years.

In February, he tweeted that his Democratic friends “can’t stand being reminded of the century-long vicious, racist, bigoted, KKK, segregationist, history of their party” — and added a smiley face to the end.

His most notable embarrassment came during what he initially reported to be a “hostage situation” in a government building in Jefferson City in 2009. Kinder called in to a St. Louis television station to relay the news, and boasted, “I was the first to tweet it.” The entire incident turned out to be generated by a false report.

“Every politician wants to be recognized, but there’s a thin line between that and ridicule. And Kinder is crossing that line with each blow-up,” said a former GOP state lawmaker who still moves in Republican circles.

Kinder is still privately ridiculed for the theft of his car in his hometown in late April, the source said. Not only was his 2009 Ford Flex stolen, it was used for an attempted burglary, torched and abandoned after he left the keys in the car.

“You don’t leave your keys in the car when you’re the lieutenant governor, and you don’t say, ‘Every dollar counts’ when you’re hanging out at the Ritz,” the former lawmaker said. “If he doesn’t make himself more relevant and stop being so weird, he’s done.”

Kinder’s temperament could also ensnare his campaign-in-waiting. Republicans say he is eccentric, anxious and awkward.

“Peter’s got some odd social skills that would be more in the spotlight if he were governor,” said another former GOP state lawmaker, who claims to like both Nixon and Kinder. “Jay’s easier to talk to. Peter’s odd and quirky. He’s uncomfortable to talk to.”

The Republican Governors Association signaled it remains firmly behind Kinder, who was the only statewide elected Republican to retain his office in the 2008 wave.

“Few states have turned away more dramatically from Barack Obama and the Democrats than Missouri. Jay Nixon is right to be worried,” said RGA spokesman Mike Schrimpf.

Kinder’s camp argues that it’s far too early in the campaign to make prognostications.

“In 2009, when people were assessing the Roy Blunt-Robin Carnahan match-up, people had concerns about his ties to D.C. and we saw what happened there,” said Kinder aide Jared Craighead, a former executive director of the Missouri Republican Party. “You can of course identify Republicans who have concerns. I think there are a lot of Democrats who have been disaffected by Nixon.”

According to several sources, some of the top political hands in Missouri last year suggested Kinder should consider the Senate race instead, which would focus less on personal characteristics and more on partisan issues.

“The scuttlebutt is, somebody else better get in this race,” said the state representative.

Even if another candidate emerges, Republicans believe dissuading Kinder will be virtually impossible. Many worry Kinder is in a more arduous position than even Hulshof, whom Nixon trounced in 2008.

“He’s got a worst start that Hulshof and that’s really saying something. Hulshof was a lack of excitement, not a lack of talent. He was a decent, talented guy,” said the former state senator. “The bottom’s falling out even before we’ve got the bucket under the faucet.”